We moved to Markdown for messages formatting (and you can still use plain HTML)
You can get some idea at:
http://stackoverflow.com/editing-help
http://www.simpleeditions.com/59001/markdown-an-introduction
Online interpreter, Markdown=>HTML=>Render
Just to sharpen your teeth...
Or better, just click Preview above message text:-)
Well just to see what the HTML was getting up to... especially with more complex syntax: eg nested lists, etc...
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